COMPARISON OF NORMAL AND OPAQUE-2 MAIZE GENOTYPES USED FOR CORN COB MIX IN PIG-FEEDING

Opaque-2 (o2) maize (Zea mays L.) contributed significantly to the qua lity improvement of maize breeding in the 1960s, but did not become po pular because of a lower yield, a result of its shorter grain-filling period. This characteristic, however, could prove to be advantageous f or use in corn cob mix (CCM), which is popular in the cold-wet regions of Europe. A research program including a 3-yr field trial, an in viv o pig (Sus scrofa) study with fermented CCM, and a farm-scale fattenin g test was conducted to evaluate the prospect of o2 for CCM production and utilization. Opaque-2 yielded as much CCM at the CCM ripening sta ge (600 g kg(-1) grain DM) as did the normal version. Due to its short er grain-filling period, o2 can accumulate more assimilates at a highe r grain moisture content than the normal maize. Results from in vivo p ig trials showed that o2 was superior in N retention and in the biolog ical value of protein compared with the normal genotype. Consequently, using o2 can balance the feed value and reduce the soybean [Glycine m ax (L.) Merr.] content in the ration for fattening pigs by 27%. The qu ality of the meat of slaughtered pigs fed with o2 and less soybean was comparable to that of pigs fed with normal maize and larger supplemen t of soybean protein. Improved o2 genotypes may be an alternative sour ce of CCM production in countries where the climate is not very favora ble for soybean production and where alternative protein supplements a re not readily available.